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(CNN) -- Rescuers on Friday suspended the search for the 11 people missing from the oil rig explosion in the Gulf of Mexico, the Coast Guard announced.
"After three days of constant searching, covering more than 5,200 square miles, we've reached the point where reasonable expectation of survivors has passed," Coast Guard Rear Adm. Mary Landry told reporters Friday evening.
The Coast Guard began notifying family of the missing that they were preparing to end the search early Friday afternoon, Landry said.
The Coast Guard and the Minerals Management Service -- the agency that regulates the oil industry in federal waters -- are conducting an active search for casualties, she said.
Earlier Friday, Landry said conversations with survivors of the blast that set the oil rig Deepwater Horizon ablaze Tuesday night indicate that the missing workers "might have been in the vicinity of this explosion."
Landry said neither the Coast Guard nor BP PLC -- which leased the rig from Transocean Ltd. -- would release the names of the dead out of respect for the families. She said the workers were from Louisiana, Texas and Mississippi.
One person injured in the explosion remained hospitalized on Friday, Landry said. She said the person is "doing well" but is expected to stay in the hospital for seven to 10 days.
Landry said crews were continuing efforts to clean up a 1- by 12-mile-long oil slick spreading through Gulf waters 40 miles offshore.
She said crude oil did not appear to be leaking out of the wellhead, located 5,000 feet below the water's surface. But remote vehicles will continue surveying the scene, she said.
"We are at the ready to respond should something happen," she said. "We're going to be very forward-leaning. We can't back off from this at all."
The Coast Guard is still attempting to locate the rig, and two nearby underwater pipelines -- one owned by the Shell oil company -- have been shut down in case there is a collision, Landry said. The closest other rig is more than eight miles away, she said.
BP officials said Thursday they did not know whether oil or fuel was leaking from the sunken rig. But BP Vice President David Rainey said, "It certainly has the potential to be a major spill."
Crews had recovered 181 barrels of an oil-and-water mixture by midday Friday, Coast Guard Petty Officer Ashley Butler said. Some of the oil had evaporated from the water's surface, she said, but about 200 barrels remained.
The Coast Guard said it was also keeping a close eye on activity underwater.
It would take about nine days for the oil to reach the shore, but the Coast Guard plans to clean up any spills before that happens, Butler said.
The rig -- a mobile unit that moves to different locations in the Gulf of Mexico -- was about 52 miles southeast of Venice, Louisiana, when the explosion occurred Tuesday night. There were no indications it was a terrorist incident, the Coast Guard said.
Officials said 126 people were on board at the time of the explosion. Of the 115 accounted-for workers, 17 injured were evacuated by helicopter from the rig. An additional 94 people were taken to shore with no major injuries, and four more were transferred to another vessel, according to the Coast Guard.
The rig had been drilling for oil in its current location since January, said Eileen Angelico, a spokeswoman for Minerals Management Service.
Angelico said the agency has begun interviewing people involved in the incident as it seeks to determine what caused Tuesday night's blast.